## 1aSP8. Application of NORDEN transform to time-frequency characterization of time-varying signals.

### Session: Monday Morning, December 2

### Time: 12:00

**Author: Nai-chyuan Yen**

**Location: Physical Acoust. Branch, Naval Res. Lab., Washington, DC 20375-5320**

**Author: Manli C. Wu**

**Location: NASA Goddard Space Flight Ctr., Greenbelt, MD 20771**

**Abstract:**

The non-orthodox decomposition (NORDEN) transform developed by NASA [N.
Huang et al., ``The Empirical Mode Decomposition and the Hilbert Spectrum for
Nonlinear and Nonstationary Time Series Analysis'' (to be published)] is
designed to adaptively break down a complex time-varying signal into a sum of
several simple mode functions. Each single mode function can then be expressed
in terms of an analytic signal whose amplitude and phase vary with time and can
be displayed as a trace in a time frequency plot, the VEIN diagram, with
magnitude expressed as line thickness or color coded. This methodology of signal
analysis, unlike other traditional transform methods, i.e., Fourier,
Wigner-Ville, and Wavelet, requires no special window, preselected kernel, or
particularly selected mother wavelet and provides more detailed dynamic
information about the signal under study in terms of its dominant components and
their instantaneous frequency variation in the observation time. Several
examples from various types of acoustic signals are examined with this algorithm
to demonstrate its signal analysis capability.

ASA 132nd meeting - Hawaii, December 1996